Mixed matrix membranes comprising MOFs and porous silicate fillers prepared via spin coating for gas separation

• Fabrication of MMMs comprising MOFs and porous silicate fillers via spin coating process.
• Selection of the proper spin coating parameters for the preparation of homogeneous MMMs.
• MOFs and porous silicate fillers with diverse pore structures and particle sizes and shapes embedded in PSF matrix.
• Enhancement in H2/CH4, and O2/N2 separation performance of MMMs compared to the pure polymer.

Different types of fillers of inorganic (titanosilicate ETS-10 and mesoporous silica type MCM-41) and organic-inorganic nature (ZIF-8 and NH2-MIL-53), with different pore size (micro- and mesoporosity) and structure, diverse particle shape, and particle sizes in the 85–400 nm range were embedded in a polysulfone matrix via spin coating. Spin coating technology, widely used in the production of thin and uniform layers on porous substrates was used here to fabricate in one coating step symmetric mixed matrix membranes (MMMs) by adjusting the spinning disk velocity, rotational time, and solid concentration and volume of solution. By selecting the optimal parameters, homogeneous MMMs containing 8 wt% of the various fillers were obtained and tested for H2/CH4 and O2/N2 mixed-gas separations, achieving significant improvements over the neat polymer. While NH2-MIL-53 MMMs revealed the highest separation performance (a rise in selectivity higher than 60 % compared to the pure polymer for H2/CH4 and O2/N2 separations), ZIF-8 MMMs showed a substantial increase in permeability (from 12.7 to 51.4 Barrer for H2, and from 2.0 to 6.1 Barrer for O2). Besides, the spin coating process enhanced solvent evaporation and reduced coat production time compared to the traditional by-hand casting.

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